1. Field of the Invention
The present invention relates to a system and method for accessing a cell that take out/insert a cartridge from or into the cell, and more particularly, to a system and method for accessing a cell that move a picker mechanism, which is used for carrying the cartridge, to the front of a target cell among a plurality of cells arranged in a matrix form in a magazine, and then, take out a cartridge that has been inserted into the target cell and put the cartridge on the picker mechanism, or unload a cartridge that has been put on the picker mechanism and insert the cartridge into the target cell.
2. Description of the Related Art
Programs and data used in a computer are, in general, stored in a hard disk drive and transferred, as needed, from the hard disk drive to a main memory at execution time of the program. The hard disk drive is constantly at the risk of being damaged, and a given limitation is imposed on the capacity thereof. Therefore, a backup device that can store a large volume of programs and data with high reliability is required, even if the backup device operates at a low speed. As the backup device, a magneto-optical disk drive, a DVD drive, a tape drive, and the like are available. Among them, a magnetic tape drive is excellent in terms of reliability, storage capacity, and cost-performance, and a collective magnetic tape drive is used in order to back up a tremendous volume of data.
A magazine is mounted on the collective magnetic tape drive. The magazine is proved with a plurality of cells arranged in a matrix form. Each cell houses a magnetic tape cartridge (hereinafter, referred to merely as “cartridge”). An accessor mechanism including a picker mechanism takes out a cartridge required in each occasion from a cell that houses the cartridge and feeds the taken out cartridge to a tape drive. After completion of recording or reproduction operation in the tape drive, the accessor mechanism feeds the cartridge from the tape drive to the cell and inserts the cartridge into the cell.
It is necessary that the picker mechanism that carries a cartridge is correctly stopped at the front of the target cell in order to complete the taking-out/insertion operation of the cartridge from/into the target cell normally. The size of the conventional collective magnetic tape drive was comparatively large, and accordingly a distance between the adjacent cells was comparatively long, so that accuracy of the stop position of the picker mechanism has not been strictly required.
However, a high-capacity collective magnetic tape drive with a small size has been recently required. In order to obtain such a small-sized collective magnetic tape drive, the size of the magazine, which is a great factor that determines the size of the collective magnetic tape drive, must be reduced under the condition that the number of cartridges that can be housed in the collective magnetic tape drive should be equal or more than the number of cartridges in the conventional collective magnetic tape drive. Therefore, assuming that the same cartridges as used in the conventional tape drive are used, a distance between the adjacent cells must be reduced as much as possible. This accordingly requires an increase in the accuracy of the stop position of the picker mechanism relative to the cell. Even if a position control servo is used to improve the accuracy of an absolute stop position of the picker mechanism at shipment time, it is difficult to improve or maintain the accuracy of the stop position of the picker mechanism relative to the cell due to attachment errors, dimension errors, distortion, wear of movable parts, secular change and the like of mechanical parts constituting the magazine.